September and October are known for their huge losses in the market. September is the worst performing month on average and is the only month with a median monthly loss starting back in 1950.

September is also the only month in which there were more negative years than positive: 53% of Septembers since 1950 have been negative while only 47% have been positive. The S&P 500 is down 0.33% since the beginning of the month, as of end of day trading on Wednesday.